Efisiensi Sirip Berbentuk Silinder

Abstract

Abstract : To cool the processor, when the computer is running, usually processor fitted with fins. With the fin, heat from the processor can be transferred to the air around the fin become larger. This study aimed to obtain the relationship between (1) (Lc+0,25D)((2h/(kD))0.5 with an efficiency η (2) Lc3/2 (hk/Am)0.5 with an efficiency η (3) Lc((π/Ao)1/2(h/k))0.5 with an efficiency η (4) Lc5/4 (((3,14/V)1/2)(h/k))0,5 with an efficiency η and (5) (Lc3/2)((3,14/S)(h/k))0.5 with efficiency η. In this study, geometry of fin is cylinder. Material of fin is metal, long of fin is L=Lc, and diameter of fin is D. All the surfaces of fin contact with the fluid. The initial temperature of fin is uniform, T=Ti. Then fin is placed in the new environment. Temperature of the new environment is T∞, coefficient of convection heat transfer is h. Temperature of fin base is Tb. Value of T∞, Tb and h are maintained at a fixed value from time to time. In this study, value of Tb is equal to Ti. The density ρ and specific heat c of fin material is considered uniform and unchanging, while value of thermal conductivity k varies with temperature or k=k(T). Conduction heat flow that goes on in the fin is assumed to take place in one direction, perpendicular to base of the fin or in the direction x. The study was conducted with the sequence of steps : (1) calculating the temperature distribution of the fin on the unsteady state, (2) calculating the actual heat flow rate released by the fin on the unsteady state, (3) calculating the heat flow rate released by fin if all the surfaces of fin which make contact with the fluid, have the same temperature with a temperature of fin base, (4) calculating the value (Lc+0,25D)((2h/(kD))0,5, Lc3/2(hk/Am)0,5, Lc((π/Ao)1/2(h/k))0,5, Lc5/4(((3,14/V)1/2) (h/k))0,5, (Lc3/2)((3,14/S)(h/k))0.5 and fin efficiency η on the unsteady state (5) drawing graphs. Calculation of temperature distribution on fin on unsteady state was done by numerical simulation with finite difference method. Finite difference method used is an explicit method. The result of study, show that (1) If the value of (Lc+0,25D)((2h/(kD))0,5 ; Lc 3/2(hk/Am)0,5 ; Lc((π/Ao)1/2(h/k))0,5 ; Lc 5/4(((3,14/V)1/2)(h/k))0,5 and (Lc 3/2)((3,14/S) (h/k))0,5 getting bigger, then the value of fin efficiency η decreases. (2) if the value of convection heat transfer coefficient h getting bigger, then the value of fin efficiency η smaller (3) For steady-state, if the value of thermal conductivity of materials increases greater then the value of fin efficiency η increases.

Keywords : Finite difference method, Fin, Efficiency, Unsteady state, Explicit